At the annual Take Back America conference of liberal activists Wednesday, Senator Clinton did not get the rousing reception that her nearest competitors for the Democratic presidential nomination did the day before. And when she got to discussing Iraq – specifically, when she stated that "the American military has succeeded" and "it is the Iraqi government that has failed" – a handful of activists took to their feet, waved signs, and booed.

Clinton was booed at the same convention a year ago, leading to questions of whether her expected presidential run would be hindered by tepid enthusiasm among many on the Democratic left. Now, as front-runner for her party's nomination both in national polls and in some polls of early-primary states, she faces a more acute question: Can a candidate perceived as a centrist by many in the party's activist liberal wing win the nomination?

The booing "reminds that relatively strong ... portion of the Democratic primary electorate of her apostasy, so to speak, with respect to an issue that's very important to them," says Bruce Buchanan, a political scientist at the University of Texas at Austin, referring to Clinton's vote in 2002 authorizing the Iraq war. "I guess that can't be good for her. On the other hand, she's still ahead in the polls and is climbing, so it obviously is not fatal among Democrats at this point."

Not only has Clinton picked up steam in the polls of late, but she is also gaining among self-described liberals. In a Gallup poll of Democratic voters taken in early June, which showed her in a dead heat for the nomination with Illinois Sen. Barack Obama, she got 25 percent of the liberal vote. By mid-June, she had regained her overall lead over Senator Obama, 33 percent to 21 percent, and was up to 30 percent among liberals.

The earlier poll showing Obama up by 1 point overall may have been an anomaly – national polls have generally shown him trailing Clinton by a figure outside the margin of error. Clinton's rise among liberals, however, could be telling. The party's hunger for a victory in 2008 only grows stronger, and the electability factor looms large. Just as maverick candidate Howard Dean flamed out in 2004 in the Iowa caucuses over concerns about electability, it may be that some liberals are concluding that Clinton's experience and organization give her the most electable package.

In an election that analysts expect will be fought in the center, unlike the last two presidential races, Clinton's centrist credentials could be a plus. And getting booed by CodePink activists can't hurt her image among centrists. But she has to get nominated first.

Another element feeding into the overall calculus is that, on the whole, the Democratic field has moved to the left in recent months. While Clinton has refused to apologize for her vote to authorize the Iraq war, she took the liberal position – along with Obama – recently in her vote not to approve continued funding for the wars in Iraq and Afghanistan.

On other issues, Clinton has positioned herself further to the left than she was a year ago. She now talks of universal health coverage, not just coverage for children. She voted against a free-trade agreement with South Korea, putting her to the left of her husband, the ex-president, who was a big advocate of free trade.

Still, says Dick Bennett, an independent pollster based in New Hampshire, "the real liberals are not with her."

Clinton's biggest strength is with women voters, who back her by a wide margin over other Democratic candidates. The bonus, says Mr. Bennett, is that she is attracting women supporters who are not normally as involved in politics as the left-wing activists in the Democratic Party.

"They're fed up with men running the country, so she can let the left wing boo her, because she's got the women," says Bennett. "My only question is, can she keep them involved and interested."

Clinton has also garnered attention this week for a campaign video that mimics the final episode of "The Sopranos." Its purpose is to announce the winner of a contest to pick the theme song of her campaign ("You and I," sung by Celine Dion). The aim of the video – showing Clinton and husband Bill in a diner in Westchester, N.Y. – is to show that she has a sense of humor, her campaign says.

But it remains to be seen if Clinton can shake off the high negatives in polls (in the mid to high 40s among all voters) that have dogged her since she began her own political career in 2000. Most Americans have a firm view of her, positive or negative, and the fame that has helped her to a lead spot in the Democratic polls may make it hard for her to rise much higher.